That call to arms was delivered by Barry Goldwater at the 1960 Republican convention to implore members of the then-youthful conservative movement to hold their noses and rally around Richard Nixon's candidacy.

Neal Freeman, a battle-scarred veteran of the conservative movement -- he was a correspondent for National Review and the producer of William F. Buckley's TV show, "Firing Line," among other tours of duty -- recently echoed Goldwater's clarion call for a different cause. It is time for conservatives to get to work on updating or even reinventing what it means to be a conservative. The conservatism of the last 50 years, programmatically, politically and psychologically, is in dire need of rejuvenation.

One sign of the exhaustion, Freeman writes, "is that the largest and most urgent issues are left unaddressed by any of the entrenched interests. Incumbent politicians deal with old issues. Movements ride new issues."

The most obvious such issue is the exploding debt, which both parties have decided is something they should only care about when trying to unseat their rivals, if at all.

But the challenge of the debt is a bipartisan or, more aptly, a nonpartisan one, simply because the math doesn't care about your politics. The pressing question for conservatives is, simply, "What is a conservative?"

"Are we free traders or fair traders?" Freeman asks. "Do we want open borders or high barriers? Can we save public education or should we euthanize it?"

Part of the dilemma is that in the modern era, Republican presidents define for many Americans (particularly in the media) what conservatism is, just as Democratic presidents tend to define what liberalism is. That may not be true in the eggheadier or more ideologically pure corners of the left and right, but for lots of normal Americans, that's just how it works. Conservatism, in journalistic shorthand, is largely whatever constitutes the "Trump agenda" at any given moment, just as liberalism was whatever Barack Obama wanted to do when he was president.

But this is a remarkably recent development, and the fact that we assume it should work this way is a symptom of the polarization of the moment, which recasts partisan loyalty as philosophical principle.

Lyndon Johnson did not define liberalism for legions of left-leaning activists and voters, nor did Richard Nixon define conservatism among the ranks of right-leaning ones (which is why Goldwater felt it necessary to plead with conservatives to support Nixon).

Indeed, despite the fact that modern American conservatism allies itself with an old, even ancient, political tradition, it's largely forgotten that it is arguably the youngest of political movements in America -- certainly younger than progressivism, socialism or libertarianism (in all of its strains from anarchism to classical liberalism).

I understand very well that conservatives often bristle at the idea they need to change with the times. As the famous line from (the far from famous) Lucius Cary, 2nd Viscount Falkland, goes, "where it is not necessary to change, it is necessary not to change."

But we forget that the conservative movement's strength came from the fact that it was armed with new arguments from diverse intellectual sources. More importantly, its vigor stemmed from the fact that these various strains of conservatives were eager to argue amongst themselves. There are arguments aplenty on the right these days, but the vast majority of them are arguments over a specific personality -- Donald Trump -- not a body of ideas. And to the extent that there are arguments about ideas, they tend to be subsumed into the larger imperative to attack or defend Trump.

As I've argued before, the best thing Trump did was to shatter the calcified and sclerotic policy agenda of Reaganism. To paraphrase "Ghostbusters," he was not the form of destroyer I would have picked, but the destruction was necessary nonetheless.

Don't misunderstand me: Reagan was the indispensable man for his time. But the challenge for conservatives -- at least my brand of conservatives -- is to find ways to apply Reaganite principles to our times.

It is possible, all too possible, that the Reaganites will fail to win the necessary arguments ahead. But that is not an argument against having those fights, for the Reaganites will surely lose them by default if they don't engage. We need more arguments -- but the right arguments.